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    Volume 11, Issue 2 (July 2021)

    Special Issue Paper

    Study of Weldability for Aluminide Coated Steels through A-TIG Welding Process

    (Received 29 October 2020; accepted 2 April 2021)

    Published Online: 19 July 2021

    CODEN: MPCACD

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    Abstract

    To achieve higher efficiency in high-temperature environments, 9Cr-1Mo steels (also known as P91 steels) are promising candidates in power plants, petrochemical industries, heat exchangers, and nuclear applications. To enhance the performance against harsh environments, such as high-temperature oxidation and corrosion during operations, adding aluminum oxide (Al2O3)/iron aluminide (FeAl) coating through the aluminizing process has been found promising. Such coatings have been considered reliable for resistance to liquid-metal corrosion against flowing lead-lithium liquid breeders and against tritium permeation in blanket modules of fusion reactors. However, the welding process for aluminized coated steels is a challenge and is scarcely reported. The aluminum-rich coating at the top may alter the metallurgy of weld metal and subsequently the mechanical properties after welding. To investigate the same, preliminary bead-on-plate trials with a novel activated-tungsten inert gas welding process has been attempted for the first time. Bead-on-plate welding samples were prepared (with the same welding parameters) with five different fluxes, such as iron (III) oxide (Fe2O3), nickel (II) oxide (NiO), copper (II) oxide (CuO), cobalt tetroxide (Co3O4), and Al2O3, for aluminized coated 9Cr-1Mo steel. The resultant weld metal microstructure was evaluated using optical and electron microscopy, elemental analysis using energy-dispersive X-ray spectroscopy, phase analysis using X-ray diffraction, and Vickers hardness testing. It was observed that the presence of oxide-type fluxes results in arc constriction, which thereby affects the depth of penetration. The weld metal prepared with Fe2O3 flux demonstrates a superior depth-to-width ratio compared to other fluxes. An analysis for delta ferrite was also carried out and was observed to be present in Fe2O3 flux welds only. A detailed analysis of the weld metal under different activated fluxes is presented in the paper. The outcome of this work presents the feasibility of the welds of aluminized 9Cr steels as relevant for fusion reactor applications.

    Author Information:

    Zala, Arunsinh B.
    FCIPT, Institute for Plasma Research, A10/B, Sector 25, GIDC Electronic Estate, Gandhinagar,

    Homi Bhabha National Institute, 2nd Floor, BARC Training School Complex, Mumbai, Maharashtra

    Jamnapara, N. I.
    Homi Bhabha National Institute, 2nd Floor, BARC Training School Complex, Mumbai, Maharashtra

    FCIPT, Institute for Plasma Research, Gandhinagar

    Badheka, Vishvesh J.
    Pandit Deendayal Energy University, Department of Mechanical Engineering, Raisan, Gandhinagar, Gujarat

    Sasmal, C. S.
    Fusion Blanket Division, Institute for Plasma Research, Gandhinagar,

    Sam, Shiju
    Advanced Tokamak Division, Institute for Plasma Research, Gandhinagar,

    Ranjan, Mukesh
    Homi Bhabha National Institute, 2nd Floor, BARC Training School Complex, Mumbai, Maharashtra

    FCIPT, Institute for Plasma Research, Gandhinagar


    Stock #: MPC20200168

    ISSN:2379-1365

    DOI: 10.1520/MPC20200168

    Author
    Title Study of Weldability for Aluminide Coated Steels through A-TIG Welding Process
    Symposium ,
    Committee A01